One method of making coffee includes passing heated water through coffee grinds in order to infuse the water with coffee flavour and aroma. A common type of coffee maker that employs this method is the so-called “rip-type” coffee maker.
In order to make good coffee the water temperature should be at substantially 95° C. for 95% of the brew time, and the coffee the water should evenly wet the grinds.
Drip-type coffee makers comprise a water reservoir and a brew basket for receiving coffee grinds. A delivery tube or other water passage takes water from the water reservoir, through an in-line water heater and delivers it to a spreader above coffee grinds in the brew basket. The heated water passes through the coffee grinds and into a carafe. There are two problems associated with the above method.
Firstly, the heated water must pass through delivery tubes and the air gap between the spreader and brew basket before reaching the coffee grinds. During this time substantial heat can be lost from the water, particularly during the early stages of brewing when the delivery tube and air gap have not had time to heat up. Thus, the water temperature in the brew basket will always be lower during the initial stages of the brewing cycle. This lowers the temperature of the final coffee beverage and affects its quality.
Secondly, the spreader attempts to distribute the heated water evenly over the coffee grinds however, the heated water generally flows through the centre portion of the brew basket. There is typically less wetting of the coffee grinds at the outer edges of the brew basket. This results in uneven extraction of the coffee grinds and has an adverse affect on the quality of the coffee beverage.